What is the function of a varistor in electrical circuits?
1 Answer
A varistor, short for "variable resistor," is an electronic component used in electrical circuits to protect sensitive devices and components from voltage spikes and surges. It is also known as a voltage-dependent resistor (VDR) or metal oxide varistor (MOV).
The primary function of a varistor is to act as a voltage regulator and transient voltage suppressor. When a normal operating voltage is applied across a varistor, it exhibits a high electrical resistance, similar to a regular resistor. However, when an overvoltage or voltage surge occurs, the varistor's resistance drops significantly, allowing it to conduct current and divert the excess voltage away from the protected components.
Here's how a varistor works in electrical circuits:
Normal operation: During regular conditions, when the voltage across the varistor is below its threshold (specified voltage), it remains in a high-resistance state. This means it does not interfere with the circuit's normal operation.
Overvoltage protection: When a voltage spike or transient surge occurs, such as lightning strikes, power surges, or sudden changes in the power supply, the voltage across the varistor rises above its threshold. At this point, the varistor's resistance decreases rapidly, becoming a low-impedance path for the excess current.
Diverting excess voltage: By providing this low-resistance path, the varistor effectively shunts the extra current away from the sensitive components that need protection. The voltage across the protected components is clamped to a safe level, preventing potential damage to them.
Varistors are commonly used in various electrical and electronic devices, including power supplies, surge protectors, voltage regulators, and electronic equipment. Their ability to absorb and dissipate transient voltage spikes makes them valuable for safeguarding sensitive and costly components from potential harm caused by voltage irregularities in the power supply.
The primary function of a varistor is to act as a voltage regulator and transient voltage suppressor. When a normal operating voltage is applied across a varistor, it exhibits a high electrical resistance, similar to a regular resistor. However, when an overvoltage or voltage surge occurs, the varistor's resistance drops significantly, allowing it to conduct current and divert the excess voltage away from the protected components.
Here's how a varistor works in electrical circuits:
Normal operation: During regular conditions, when the voltage across the varistor is below its threshold (specified voltage), it remains in a high-resistance state. This means it does not interfere with the circuit's normal operation.
Overvoltage protection: When a voltage spike or transient surge occurs, such as lightning strikes, power surges, or sudden changes in the power supply, the voltage across the varistor rises above its threshold. At this point, the varistor's resistance decreases rapidly, becoming a low-impedance path for the excess current.
Diverting excess voltage: By providing this low-resistance path, the varistor effectively shunts the extra current away from the sensitive components that need protection. The voltage across the protected components is clamped to a safe level, preventing potential damage to them.
Varistors are commonly used in various electrical and electronic devices, including power supplies, surge protectors, voltage regulators, and electronic equipment. Their ability to absorb and dissipate transient voltage spikes makes them valuable for safeguarding sensitive and costly components from potential harm caused by voltage irregularities in the power supply.